/Engine/Source/Runtime/Core/Public/Serialization/PackageWriter.h
This may only be called after aBeginPackage()call has been made to signal the start of a package store transaction
void WritePackageData ( const [FPackageInfo](API\Runtime\Core\Serialization\IPackageWriter\FPackageInfo) & Info, [FLargeMemoryWriter](API\Runtime\Core\Serialization\FLargeMemoryWriter) & ExportsArchive, const [TArray](API\Runtime\Core\Containers\TArray)< [FFileRegion](API\Runtime\Core\Serialization\FFileRegion) > & FileRegions )